Active Site Modeling of Fe/Cu Containing Metalloenzymes

含铁/铜金属酶的活性位点建模

• 批准号: 6666105
• 负责人: ESTELLE L LEBEAU
• 金额: $ 12.6万
• 依托单位: CENTRAL MICHIGAN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6666105
• 关键词: active sites; biomimetics; copper; cytochrome oxidase; enzyme mechanism; enzyme model; enzyme structure; heme; metalloenzyme; protein engineering; synthetic enzyme

DESCRIPTION (provided by applicant): Cytochrome c oxidase (CcO) is an important enzyme in the respiratory cycle of many life forms. Once in the cell, oxygen binds to the enzyme and is converted to water and energy. A study of the structure of cytochrome c oxidase and similar proteins, like hemoglobin, will allow for a better understanding of the mechanism of oxygen conversion into water and the overall cellular respiration process. Toward achieving this understanding, a series of reduced, heteronuclear heme-copper (Fe II/Cu I) or reduced Fe II-porphyrin complexes that are designed to mimic the active centers of these biological heme-containing enzymes will be synthesized within sol-gel matrices. Reactivity studies will be performed to further elucidate influences of subtle changes in environment upon complex activity toward oxygen binding and subsequent reduction to water. Included amongst these fully-reduced biomimics are carbonmonoxy and isocyanide ligated derivatives of covalently-linked model compounds because these ligands stabilize the reduced states, Fe II and Cu I. Reactivity studies, focusing upon photolytic displacement of these ligands, will be performed to further elucidate influences of subtle changes in ligand coordination environment upon complex reactivity toward 02 binding and ligand recombination. Tethering the heme to the sol-gel matrix will inhibit direct heme-heme reactivity, similar to the protein backbone in natural systems. A ligand bridged Fe-X-Cu center has been implicated in the CcO catalytic cycle. Several "mixed valence" (Fe II/Cu II) tethered heme/copper complexes will be synthesized and characterized to mimic the spectral and reactivity characteristics of the native enzyme. These complexes may have relevance with regard to the energy translocation and storage required for proton pumping across the mitochondrial membrane in CcO. This aspect of the project is designed to answer the questions regarding ligand shuttling after photoinitiated intervalence charge transfer in these novel bimetallic systems.

描述（由申请人提供）：细胞色素c氧化酶（CcO）是许多生命形式呼吸循环中的重要酶。一旦进入细胞，氧与酶结合并转化为水和能量。对细胞色素c氧化酶和类似蛋白质（如血红蛋白）的结构进行研究，将有助于更好地了解氧气转化为水的机制和整个细胞呼吸过程。为了实现这一理解，一系列的减少，heterophosphore-copper（Fe II/Cu I）或减少Fe II-卟啉配合物，旨在模仿这些生物血红素含酶的活性中心将合成溶胶-凝胶基质。将进行反应性研究，以进一步阐明环境中的细微变化对氧结合和随后还原为水的复合物活性的影响。在这些完全还原的仿生物中包括共价连接的模型化合物的碳单氧基和异氰化物连接的衍生物，因为这些配体稳定还原态Fe II和Cu I。将进行反应性研究，重点是这些配体的光解置换，以进一步阐明配体配位环境中的细微变化对O2结合和配体重组的复杂反应性的影响。将血红素束缚到溶胶-凝胶基质将抑制血红素-血红素的直接反应性，类似于天然系统中的蛋白质骨架。配体桥联的Fe-X-Cu中心已被牵连在CcO催化循环。几个“混合价”（Fe II/Cu II）束缚血红素/铜配合物将被合成和表征，以模仿天然酶的光谱和反应特性。这些复合物可能与CcO中线粒体膜质子泵送所需的能量转运和储存有关。这方面的项目是为了回答有关配位体穿梭后，在这些新的光引发的价间电荷转移系统的问题。